• Rub the grapeseed oil or mayonnaise into your palms and fingers. Take the rice in your right hand, if you are right-handed. (Or simply reverse all the instructions.) Hold the prawn (or other topping) in your left hand, across the base of your fingers.

• Place your rice on top of the fish. Put your right index finger on top of the rice. Wrap your left hand around your right index finger, squeezing gently to make a nice shape. Turn your nigiri so the fish is on top, still placed over the base of the fingers.

• Repeat the wrapping and squeezing steps to form a neat, compact piece of nigiri. Do not squash the rice together too hard; all your movements should be gentle.

• Now smooth the edges of the prawn or other topping into an organic, graceful curve, with no corners: the topping should drape elegantly over the rice.